IMMUNOFLUORESCENCE ASSAY, C3 (TISSUE)

The Immunofluorescence Assay (IFA) for C3 detects the presence of complement component 3 (C3) deposits in tissues. C3 is part of the immune system’s complement cascade, and its deposition in tissues is a sign of immune complex formation and inflammation. The test is primarily used to diagnose autoimmune and immune complex-mediated diseases, such as lupus nephritis, glomerulonephritis, and vasculitis.

This test is recommended for:

• Patients with suspected autoimmune diseases such as systemic lupus erythematosus (SLE), particularly those with kidney involvement.
• Individuals with symptoms of glomerulonephritis, including hematuria, proteinuria, and decreased kidney function.
• Patients presenting with skin rashes or vasculitis suspected to be immune complex-mediated.
• Those requiring confirmation of immune-mediated tissue injury through biopsy.

A tissue biopsy sample (usually from the kidney or skin) is collected and treated with fluorescently labeled antibodies that bind to C3. The sample is then examined under a fluorescence microscope to detect C3 deposits, which appear as bright fluorescent areas within the tissue.

• Positive result: Presence of C3 deposits suggests immune complex-mediated tissue damage, commonly seen in lupus nephritis, post-infectious glomerulonephritis, and other immune-mediated conditions.
• Negative result: Absence of detectable C3 deposits reduces the likelihood of immune complex-mediated disease, but further clinical evaluation may be necessary.

C3 deposition in tissues is a hallmark of immune complex diseases, and detecting it provides valuable diagnostic information. It helps differentiate between immune and non-immune causes of tissue damage, guiding treatment decisions and monitoring disease progression.